Types and Characteristics of Crude Oil Demulsifiers
Crude oil demulsifier is divided into SP-type demulsifier, AP-type demulsifier, AE-type demulsifier and AR-type demulsifier.
The main component of SP-type demulsifier for oilfield is polyoxyethylene polyoxypropylene stearyl ether. The theoretical molecular formula is R(PO)x(EO)y(PO)zH, where EO is polyoxyethylene; PO is polypropylene; R is fatty alcohol; x, y, and z are degrees of polymerization. SP-type demulsifiers appear as light yellow pastes. The HLB value is 10 to 12 and the demulsifier additive for crude oil is soluble in water.
AP-type demulsifier for oilfield is polyoxyethylene polyoxypropylene polyethers initiated by polyethylene polyamine. It is a multi-branched nonionic demulsifier. The molecular formula is D(PO)x(EO)y(PO:zH, where EO is polyoxyethylene; PO is polyoxypropylene; R is fatty alcohol; D is polyethylene polyamine; x, y, and z are degrees of polymerization.
AE-type demulsifier for oilfield is polyoxyethylene polyoxypropylene polyethers initiated by polyethylene polyamine. It is a multi-branched nonionic demulsifier. Compared with AP-type crude oil demulsifier, the difference is that AE-type crude oil demulsifier is two-stage polymer with small molecular weight and short branche. The molecular formula is D(PO)x(EO)yH, where EO is polyoxyethylene; PO is polyoxypropylene; D is polyethylene polyamine; x and y are degrees of polymerization.
AE is a two-stage multi-chain crude oil demulsifier and is also suitable for demulsification of asphaltene crude oil emulsions. The more surfactant on the surface of asphalt-based materials, the greater the viscosity, the smaller the oil-water density difference and the more difficult it is to demulsify. However, the demulsification speed using AE-type demulsifier additive for crude oil is fast. At the same time, AE-type demulsifiers are good anti-wax viscosity reducers.
AR-type demulsifier additive for crude oil is composed of alkyl phenolic resin (AR resin), polyoxyethylene, polyoxypropylene polymer and a new oil-soluble nonionic demulsifier. The HLB value is 4 to 8 and the demulsification temperature is as low as 35 to 45 °C. The molecular formula is AR(PO)x(EO)yH, where EO is polyoxyethylene; PO is polyoxypropylene; AR is resin; x, y, and z are degrees of polymerization.
There are many types of demulsifier for oilfield. According to the classification of surfactants, they can be divided into cationic, anionic and nonionic demulsifier. Anionic demulsifier for oilfield is carboxylates, sulfonates and polyoxyethylene fatty sulfate salts, etc. They have great effects but are easily affected by electrolytes and other disadvantages; cationic demulsifier for oilfield is mainly quaternary ammonium salts, which have a significant effect on thin oils but are not suitable for heavy oils and aged oils; nonionic demulsifier mainly include block polyethers initiated by amines, block polyethers initiated by alcohols, alkyl phenolic resin block polyethers, phenolic resin block polyethers, silicon-containing demulsifiers, ultra-high molecular weight demulsifier, polyphosphates, modified flame-retardant polyethers and imidazoline products.
Crude oil demulsifier is representatives of two-ion demulsifier.